Inductance coil



Patented May 15, 1923.

UNITED STATES PATENT OFFICE.

ERNEST G. DANIELSON, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO E. T. CUNNINGHAM, OF SAN FRANCISCO, CALIFORNIA.

INDUCTANCE COIL.

Application filed Kay 25, 1921. Serial No. 472,504.

To all whom it may concern:

Be it known that I, ERNns'r G. DANIEL- SON, a citizen of the United States, and a resident of the city and county of San Francisco, State of California, have invented certain new and useful Improvements in Inductance Coils, of which the following is a specification.

The invention relates to inductance coils for use in radio receiving systems and to mountings for said coils so that the mutual inductance between the primary and sec ondary circuits may be varied and so that the actual inductance of either circuit may be varied. Inductance coils for this purpose are usually mounted on a support, on which the primary coil is pivotally mounted, so that its position with respect to the secondary coil may be varied to vary mutual inductance of the coupling. The coils are detachably mounted on the support and when it is desired to change the inductance of a circuit, it has been necessary to remove the inductance coil and to substitute therefor, another coil having a different induc- 'tance. This required that the operator have a plurality of inductance coils of different value. In accordance with my invention, I mount a switching device on the coil whereby 'the actual inductance of the coil may be varied, by varying the number of turns in circuit.

An object of my invention, therefore, is to provide an inductance coil for use in tuning radio receiving circuits which is provided with switching means whereby the number of turns of the coil in circuit may be varied.

Another object of the invention is to provide switching means mounted directly on the detachable coil so that the inductanct of the circuit may be readily varied.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forth at length in the following description, where I shall outline in full, that form of the invention which I have selected for illustration in the drawings accompanying and forming part of the present specification.

In said drawings:

Figure 1 is a perspective view of the inductance mounting, with the coils mounted thereon.

Fig. 2 is a front elevation of an inductance coil provided with the switching means.

Fig. 3 is a side elevation of the inductance coil.

Fig. 4 is a diagrammatic representation of the switching arrangement of the coil.

, The inductance coil is preferably a lattice Wound hollow cylindrical coil 2, supported in a strap 3 of non-conducting material, to which is secured a coil plug 4, of insulating material, such as bakelite. The coil plug is provided with a, projection 5 and a socket 6, for interengagement with complementary socket and projection on the panel plug. Mounted on the coil and secured thereon by the strap 3 is a switch block 7 of bakelite or other insulation, having on its face a series of contacts 12, 13, 14 and 15 which are connected by taps 16, with different parts of the coil, the connections being preferably such, that one-fourth, one-half, three-fourths or the whole of the coil may. be placed in circuit. Mounted on the switch block is a contact arm 17, which is movable by the knob 18 over the contacts, to vary the number of turns in circuit. The switch arm is usually directly connected to one coil connection, such as the plug 5, and the coil is connected to the other connection, such as the socket 6.

The switch block is preferably disposed on the opposite side of the coil from the coil plug 4, so that the knob 18 may be readily reached by the operator to vary the inductance of the coil.

A radio receiving system usually includes three associated inductance coils, comprising a secondary coil 2* which is usually stationary and primary coils 2 mounted on both sides of the secondary coil for movement with respect thereto to vary the inductive coupling between the primary and secondary circuits. The coils are mounted on a panel 21, supported on a base 22, and the panel is provided with a fixed panel plug 23, to receive the plug connections of the secondary coil 2 and with pivoted panel plugs 24, mounted on opposite sides of the stationary plug. The plugs 24 are mounted by vertical pivots 25 to the brackets 26 which are secured to the panels, and are formed to receive the coil plugs of the primary coils. By moving the primary coils on their pivots, the mutual inductance between the primary and secondary circuits may be readily varied and by moving-a switch arm, the actual inductance in either circuit may be varied. It is understood that it is not essential that all of the coils be -provided with switching means.

1. Ifh 'an induction coil mounting, means providing terminals for the coil, means for varying the number of effective turns of the coil, and a common means for tightly holding both of said latter means against the outside periphery of the coil structure.

2. In an induction coil mounting, a terminal block for the coil, said bloc-k serving block and the turn-varying means upon the periphery.

3. In combination, an inductance'coil, a

pivotal support for said coil about an axis located outside of the coil, a terminalblock attached to the coil and engaging said support for providing connections to the coil and for supporting it on the pivotal support, a switch-for varying the number of turns in the coil, and means whereby the switch as well as the terminal block are secured to the outside periphery of the coil.

In testimony whereof, I have hereunto set my hand.

ERNEST G. DANIELSON. 

